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Mesa Etching Process Using Photolithographic Techniques

Publishing Venue

IBM

Related People

Pillot, P: AUTHOR

Abstract

Described is a process for a mesa etching technique, to provide mesa transistors manufactured in accordance with integrated circuit procedures, mainly characterized in that: the photoresist is applied directly on the silicon substrate as a mask for etching according to the desired patterns. This is achieved by using the association of a thick-resist layer and a high-speed etching composition, which permits the provision of precise etched patterns.

Country

United States

Language

English (United States)

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Mesa Etching Process Using Photolithographic Techniques

Described is a process for a mesa etching technique, to provide mesa
transistors manufactured in accordance with integrated circuit procedures, mainly
characterized in that: the photoresist is applied directly on the silicon substrate
as a mask for etching according to the desired patterns. This is achieved by
using the association of a thick-resist layer and a high-speed etching
composition, which permits the provision of precise etched patterns.

With the reference to the drawings, the detailed process steps are as follows:

1) A silicon substrate 10 is provided at the location where the d'- desired
mesa etch is to be made between two integrated transistors, not shown. First, an
adhesion treatment is achieved, for example, a hexamethyl disilazane-flugene
(1,9) mix is used to improve subsequent adhesion on the photoresist material.

2) A layer of a photoresist material 11, is deposited onto the entire surface of
the substrate to obtain a thickness of about 7mu. Typically thin film resist KTFR'*
is appropriate.

3) Then the coated substrate is exposed through a mask 12 to UV radiation.

4) Just between exposure and development, the coated substrate is baked
for 1/2 h at 120degrees C to achieve the polymerization of the resist and improve
adhesion.

During the develoement (xylene: 30 sec. and buthyl: 30 sec) the unexposed
portion is removed. This step is followed by a drying operation during 2 min 30
sec.